As depicted in FIGS. 1A-1B, a typical axial/in-line laparoscopic tool device 100 generally has five main components: a handle 102, an outer shaft 104 extending longitudinally from the handle, an actuation rod 106 extending through the outer shaft, and an actuatable end effector 110, disposed at the distal end of the device. The handle 102 illustrated is an “in-line handle”, which has a stationary handle portion 112 attached to the outer shaft 104 and an actuatable handle portion 114 attached to the actuation rod 106. Actuation of the actuatable handle portion 114 by pivoting relative to the stationary handle portion 112 moves the actuation rod 106 axially within the outer shaft 104 to operate the end effector 110. The actuatable handle portion 114 typically is biased into an open position by a spring such as a hinge spring 115. Some existing devices include a ratchet mechanism to hold the handle portions 112, 114 in a selected position relative to each other. As shown in FIGS. 1A-1B, a known ratchet has a pawl arm 118 that engages a ratchet-toothed arm 120. The ratchet is biased into a disengaged position, but it can be selectably engaged/disengaged by actuating and holding in place a ratchet lever 122 or it can be lockedly disengaged by actuating a separate, transversely mounted, ratchet-locking button 124 that holds the ratchet-toothed element 120 at an angle configured to remain disengaged from the pawl element 118. With this configuration, a user may be required to use his/her opposite hand and/or to change grip position on the handle 102 to reach and actuate the ratchet-locking button 124.
Although different variations of each of the above components have been introduced into the art, there exists a need for designs that provide efficiency in manufacturing, and that provide surgeons and other users with ergonomic features to enhance safety and ease of use. In particular, there is a need for a handle design that includes an easy-to-use locking feature having a minimal number of components to provide for ease of assembly and durability. In particular, there is a need for a durable handle design including a ratchet mechanism that can easily be operated by the user's gripping hand from a variety of grip positions, without requiring a user to significantly alter his/her grip, or to use his/her other hand to engage, disengage, and lock the mechanism.